1. Field of the Invention
The present invention relates to an image-sensing apparatus for compensating video signal of a plurality of channels, and especially relates to an image-sensing device for generating a plurality of channel outputs and for compensating an output signal level in each channel.
2. Description of the Related Art
Recently, a micro-fabrication technology has been developed remarkably for manufacturing large scale semiconductor integrated circuit (LSI). In addition, there is a need in the market for image-sensing apparatus which provides high resolution pictures. The image-sensing apparatus includes an image-sensing device which converts an optical image into a video signal, and various signal processors to conduct signal conditioning on the video signal outputted from the image-sensing device.
In order to obtain high resolution pictures, a number of pixels in the image-sensing device becomes bigger because more pixels in the same area provide higher resolution pictures. Accordingly, a number of pixels corresponding to one scanning line in the image-sensing device becomes bigger.
However, an output time of video signal for one scanning line is fixed by the television format specification. In other words, in order to obtain video signal from an image-sensing device having more pixels in one scanning line, it naturally requires a clock signal having higher frequency to read-out video signal from such the image-sensing device.
In case that a clock signal has higher frequency, various signal processing circuits in a subsequent stage need to operate in such a clock signal of higher frequency, which limits a circuitry design for image-sensing apparatus. In addition, the processing circuit operating in high frequency clock signal requires various arrangements to avoid an influence of noise or radiation, etc.